12 January 2018

Fuel Conundrum

The Precious has a compression ratio of 10.7 to 1.

The owner's manual states: "[U]se premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but your vehicle’s acceleration could be slightly reduced, and you might notice a slight audible knocking noise, commonly referred to as spark knock."

The grades of gas in FL tend to be 87, 89 and 93 octane.  Those three grades can also be up to 10% ethanol.

Ethanol free gas is available in 90 octane.

Today the prices were...

87 octane regular unleaded $2.349
89 octane plus unleaded $2.649
93 octane premium unleaded $2.949
90 octane ethanol free unleaded $2.909.

I remember before ethanol became mandatory that my car got better mileage.  I wonder if being short an octane from recommended matters all that much; cheaper per gallon and going farther on each gallon sure seems worth the trade.


  1. You ever heard of Farmer's Subsidies? This was so far the biggest one. Corn prices shot up because of the ethanol mandate, so much so that the Mexican citizens were bitching the flour was scarce and expensive all of the sudden because corn was being used to fuel gringo cars and not making tortillas for the beans.

    But less farting and ethanol makes for better environment.

    1. Dude, I am from Iowa; grandson of pig farmers, I know what farmer's subsidies are. Grampa never turned one down. My favorite was the federal grant to leave plots fallow. Grampa once said he made more money not-farming the land than farming it. Specializing in pigs meant a lot less land was used than he owned.

      In Iowa the mid-grade, 89 octane was nearly always the ethanol blend and was often 10% or more cheaper than regular gas. When the feds were, in effect, paying for the ethanol AND paying the fuel suppliers to mix it in...

      Just a year ago the ethanol free stuff was more expensive than the premium.

  2. I sold my premium gas only Toyota five years ago. Premium was 20 cents more per gallon for the five years I had it.

    The difference has really spread out since I went from sporty little car to my Exploder.

    1. The first time it mattered to me the spread was a nickel per step; with premium being about 10% more than regular.

      That held for a long time.

      Now it's near 25% more for 6 measly octane.


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